Bird tolerance to humans in open tropical ecosystems

Animal tolerance towards humans can be a key factor facilitating wildlife–human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene.


Field-specific reporting
Please select the one below that is the best fit for your research. If you are not sure, read the appropriate sections before making your selection.

Life sciences
Behavioural & social sciences Ecological, evolutionary & environmental sciences For a reference copy of the document with all sections, see nature.com/documents/nr-reporting-summary-flat.pdf

Ecological, evolutionary & environmental sciences study design
All studies must disclose on these points even when the disclosure is negative.

Study description
Research sample Sampling strategy
We did not study humans.
We did not study humans.
We did not study humans.
We did not study humans.
We aimed to identify a key life-history, ecological and environmental traits that best predict direction and magnitude of tolerance of savannah birds towards humans (measured as flight initiation distance) by using Bayesian phylogenetically-and spatially-informed analyses.
Our sample covers birds (class Aves) inhabiting open tropical ecosystems of three continents (Africa, South America, Australia) for which data on escape distances, life history, ecology and other traits were available. We tried to cover as much sites in open tropical ecosystems as possible. Moreover, at most sampling sites, we sampled as much bird species and individuals as possible. We generally did not focus on population of particular species.
Altogether, we collected 14,998 flight initiation distances for 953 bird species (120 families and 32 orders). However, this sample was reduced to 10,249 observations for 842 species (in full dataset) and 5,400 observations for 425 species (in dataset for passerines), respectively, because some predictor values were missing for some species. For details on sampled localities, populations, and species, see information at the Open Science Framework repository (https://doi.org/10.17605/OSF.IO/BSPQX).
We were primarily interested in escape behaviour of birds when facing approaching human. Because this type of behaviour is context, population, and species-specific, we put together data from as sites, populations, and species as possible. The sample sizes in the final analyses were determined by the data availability for used variables.
Data on flight initiation distance, starting distance, flock size, habitat type, and site position were collected directly in the field by the authors of the study. For further details and individual-based measurements, see information at the Open Science Framework repository (https://doi.org/10.17605/OSF.IO/BSPQX); each sampled bird individual is assigned to a name of observer. Escape distances were estimated by a number of~1 m steps, conversion of a number of steps to metres, or using a rangefinder. Field data were then typically written down to the field notepad. Data on body mass, clutch size, wing shape, migratory behaviour, and ground foraging were extracted from the literature by PM. Data on season, tree cover and altitude were extracted using open online tools and ArcGIS by DR. contexts. Because this type of behaviour is context, population, and species-specific, we put together data from as sites, populations, and species as possible. To improve robustness of our results, we sampled as much bird species and individuals as possible at most sites. All field data were collected using previously published protocols, briefly described also in a method section of this study. All raw data are deposited at the Open Science Framework repository (https://doi.org/10.17605/OSF.IO/BSPQX).
We took into account phylogenetic, spatial, temporal, and collector non-independence by always including phylogeny, spatial covariance matrix and species, site ID, year and collector ID as a random factors in regression models.
Most data were collected before this study started, i.e. were collected blindly regarding hypotheses tested in the present study.
All field data were collected in open tropical ecosystems of three continents (Africa, South America, Australia). The most of data were gathered in the morning (06:00-10:00) and evening (15:00-18:00) when birds are most active. Field data were collected during favourable weather, mainly during sunny days with no or weak wind. We excluded observations from large patches of habitats markedly differing in vegetation structure from open tropical habitats, such as closed forests.
Our fieldwork was conducted in one country in South America ( No import/export of samples was required to complete this study.
All fieldwork was conducted in accordance with the approved guidelines. Data were collected in public places and on private lands where no special permit was required. The method used to estimate avian tolerance towards human disturbance was designed to cause only brief and minimal disturbance to birds; in cities, this disturbance typically does not differ from standard background disturbance caused by other site visitors.
No laboratory animals have been used in this study.
Our study was observational and included 953 species of birds.
We did not collect data on the sex of animals.
Our study was observational and did not include samples collected from the field.
In Kenya, field data collection was approved by National